Hydraulic pump



Aug .9, 11960 B, A. BAILEY ETAL HYDRAULIC PUMP 2 Sheets-Sheet 2 Filed Nov. 9, 1959 BERYL A. BAILEY ALV/A G. BAILEY FIG. 2B.

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2,948,224 HYDRAULIC PUMP Beryl A. Bailey and Alvia o. Bailey, both of 601 N. Commercial St., Anson, Tex.

Filed Nov. 9, 1959, Ser. No. 851,626

Claims. (Cl. 103-46) This invention relates to hydraulic pumps and has reference to a tubing lift pump incorporating pressure operated valve switching means.

The prevalent use of pumping jacks and sucker rods in the production of oil from deep wells entails certain disadvantages which become greatly amplified in .so called slim hole production where frictional contact between sucker rods and production tubing result in appreciable power losses during a pumping cycle and increased wear upon pumping facilities. Even in production through standard bore, much of the pumping power is consumed in overcoming the inertia of the sucker rods, and the transfer of energy toa submerged pump through weightbearing mechanical members result in additional frictional losses as well as additional maintenance and replacement of bearing parts. Pumping of wells by means of surface injected fluid pressure eliminates the need for sucker rods and pumping jacks but has heretofore presented other problems associated with their operation. Among prior difiiculties has been what might,

be termed the dead center problem which involves the possibility that a submerged reciprocating pump which actuates its own reversing system might come to rest at a position of hydraulic equilibrium and cease to function; field correction could involve a costly withdrawal of pump and tubing for release. Another difiiculty of particular importance in slim hole production has'been the utilization of cylinder space to provide simultaneous pumping of production oil and evacuation of oil used to operate the pump. In addition, elimination of auxiliary tubes to deliver pressure to the pump is desirable because of the reduced number of connections required.

Accordingly, an object of the present invention is to provide a pump for oil wells and the like which may operate without a pumping jack and sucker rods and which may utilize a motor of less power for comparable pumping capacity.

Another object of the invention is to provide a pump which may be compactly constructed for slim hole pro duction.

A further object of the invention is to provide a pump which is reliable in operation and is not susceptible to dead center or equilibrium locking.

Another object of the present invention is to provide a pump of the hydraulic type and wherein the possibility of gas lock during its operation is reduced.

An additional object of the present invention is to provide a hydraulic pump which will exert a partial vacuum upon an oil reservoir during its pumping operation.

Yet another object of the invention is to provide a hydraulic pump foroil wells or the like and wherein the annular space between the casing and tubing of a Well may be used as a conduit for transmission of operating power for the pump.

These and other objects will become apparent from the followingdescription and the accompanying draw ings,1wherein: j

, 2 Figure 1 is a schematic and diagrammatic view of the invention illustrating principles of its operation. Figure 2 is a fragmentary and partially sectional view of the upper portion of the invention. Figure 2A is a fragmentary and partially sectional view of the central portion of the invention.

Figure 2B is a fragmentary and partially sectional view.

of the lower part of the invention.

Figure 3 is a sectional view taken along line 3-3 in Figure 2A. v

Figure 4 is a sectional view taken along line 4-4 in Figure 2A.

Figure 5 is a sectional view taken along line 55 in Figure 2A.

Figure 6 is a perspective view of an alternator block of the invention wherein the course of pumping fluid is changed during alternate strokes of the pump.

the invention for delivering hydraulic pressure Figure 7 is a perspective view of a bypass block of the invention with a portion thereof removed to illustrate internal features of construction.

Figure 8 is a perspective view of an actuator block of to the valve system.

Figure 9 is a perspective view of a lower valve head in accordance with the present invention.

Figure 10 is a sectional view taken along line 1010' in Figure 9.

Figure 11 is a perspective view of a schematic arrangement of passage ways relative to the opening of the valve liner.

Figure 12 is a perspective view of an actuator disc and its associated depression plate in accordance with the of a well bore.

terior wall of the casing 10 by'means well known in the largest of the threaded surfaces.

present invention.

In the drawings, a well casing 10 extends from the surface of the ground to the bottom or vicinity of the bottom Within the casing 10 the bottom stand of a tubing string 11 is threadedly engaged by an expansion joint 12 which also threadedly engages the upper end of an upper pump barrel 13. An upper valve head 14 provided with a periphery of three cylindrical and coaxial threaded surfaces of different diameters vertically oifset from one another in upwardly diminishing order of size is provided with an annular shoulder 15 (Figure 2A) centrally positioned about its lowest and largestthreaded surface. Interior threads within the lower end of the upper pump barrel 13 engage the threads above the shoulder 15 on the lowest threaded surface of the upper valve head 14. A cylindrical valve housing 16, identical in diameter to the upper pump barrel 13, is provided with interior threads at its upper end which engage the threads beneath the shoulder 15 on the largest threaded surface of the upper valve head 14. A lower threads at its opposite ends, engages the threads of the largest diameter of the lower valve head 17 below the annular shoulder 18 thereon. A reduction joint 20 threadedly engages the lower end of the lower pump barrel 19 and is also threadedly connected to the upper end of a reservoir tube 21 which may consist of one or more stands of standard tubing or a shortened length of.

the same. An annular packer 22 is secured to the inv Patented Aug. 9, 196 0 art and a conical packing gland element 23, threadedly engaged by the lower end of the reservoir tube 21, is positioned within the packer 22 and is there held with suitable pressure by adjustment of the tubing 11 at the surface of the well. The packing gland element 23 is provided with a vertical opening which corrnnunicates the reservoir tube 21 with so much of the casing as extends below the packer 22.

The lower end of an upper purnpcylinder 24 engages the smallest threaded surface of the upper valve head 14 and the cylinder projects upwardly within the upper pump barrel 13 and coaxially therewith. An upper divider cylinder 25 is coax ally positioned in and spaced from the upper pump barrel '13 and is also spaced from the upper pump cylinder 24. The lower end of the upper divider cylinder 25 engages the threaded surface of intermediate diameter of the upper valve head 14. An upper cylinder head 26 is constructed with its lower portion adapted to engage interior threads of the upper end of the upper pump cylinder 24 and with a cylindrical central portion extending radially above the top of the upper pump cylinder to press fit engagement with interior walls in the top of the upper divider cylinder 25; the upper portion of the upper cylinder head 26 extends radially above the top of the upper divider cylinder 25, but its periphery is spaced from the upper pump barrel 13. A check valve seat 27 is recessed within the upper surface of the upper cylinder head 26 and a valve ball 28 is adjacently positioned on the upper side of the seat 27. A cage 29 projects upwardly of the seat 27 about the ball 28, and a valve port 36 communicates the valve seat 27 with the interior of the upper pump cylinder 24. Perforations 31 through the wall of the upper pump cylinder 24 at a position irnrnediately beneath the upper cylinder head 26 communicate tne interior of the upper pump cylinder 24 with the annulus between that member and the upper divider cylinder 25-.

A lower pump cylinder 32 is coaxially positioned within the lower pump barrel l9 and interior threads at its upper end engage the lowest and smallest threaded surface of the lower valve head 1'7. A lower divider cylinder 33 is positioned between the lower pump cylinder 32 and the lower pump barrel 19, and interior threads at its upper end engage the threaded surface of intermediate diameter of the lower valve head 17. Walls of the lower divider cylinder 33 are spaced from the interior surface of the lower pump barrel 19 and from the exterior surface of the lower pump cylinder 32. A lower cylinder head 34 is constructed with an upper threaded surface adapted to engage interior threads in the lower end of the lower pump cylinder 32 and with a central cylindrical surface of intermediate diameter adapted for press fit engagement with the interior wall surface within the lower end of the lower divider cylinder 33. A lower portion of the lower cylinder head 34 projects radially outward below the bottom of the lower divider cylinder 33 but is spaced from the interior surface of the lower pump barrel 19. A valve seat 35 is recessed within the top of the lower cylinder head 34 and a valve ball 36 is positioned thereon; a cage 37 enclosing the valve ball 36 is attached to the top of the lower cylinder head 34. A lower pump port 355 communicates the valve seat 35 with the reservoir tube 21. Perforations 39 through the wall of the lower pump cylinder 32 at a position therein directly above the lower cylinder head 34 communicate the interior of the lower pump cylinder with the annulus between that member and the lower divider cylinder 33.

A shaft 40 extends from the interior of the upper pump cylinder 24 to the interior of the lower cylinder 32 and is slidably mounted in the upper and lower valve heads 14 and 17 through openings 41 (Figure 3) and 42 (Figures 9 and 10). An upper piston generally designated by the numeral 43 is comprised of av plurality of annular piston rings 44 and spacers 45 alternately positioned about the upper end of the shaft 40 above an annular shoulder 46 secured to the shaft 40; a nut 47 engaging threads on the upper end of the shaft 40 secures the rings 44 and spacers to the shoulder 46. In like manner, a lower piston 48 is comprised of rings 49 and spacers 50 held between a shoulder 51 and a nut 52.

A tubular valve liner 53, which provides a valve chamber, is vertically disposed within the valve housing 16 and is eccentrically positioned therein in a spaced relationship with the shaft 40; the valve liner 53 abuts the lower end of the upper valve head 14 at its upper end and its lower end abuts the upper end of the lower valve head 17. 7

Within the valve housing 16 there are a plurality of cylindrical block members comprising a manifold for transmission of fluids and selective communication of the cylinders with various hydraulic passageways as well as with the passageways of a valve mechanism. Some of the passageways are common to all of the members comprising the manifold whereas other passageways are coextensive with only one or more of the cylindrical members. In order to make the function and construction of each cylindrical member clear, those passageways common to all members are herein denoted by the same numerals. As a further aid to an understanding of the relationship of particular passageways to one another, reference is made to Figure 11 which represents certain passageways in their relationship to the valve liner 53; in order that these passageways may be clearly illustrated, the passageways and the valve liner are shown (in Figure 11) as having been rotated 90 in a counterclockwise direction with reference to Figures 6- through 9.

A cylindrcal lower actuator block 54 is positioned directly above the lower valve head 17 within the valve housing 16. An opening 55 for the shaft 40 extends vertically through the lower actuator block 54 and is coaxial with the principal axis of the lower actuator block itself. The valve liner 53 extends through a vertical opening 56 spaced from the shaft opening 55 but parallel therewith. A lower horizontal passageway 57 (shown in Figure 2A and by dotted lines in Figures 8 and 11) is formed by radially aligned openings in the valve liner 53, lower actuator block 54 and valve housing '16 and communicates the interior of the valve liner 53 with the annulus between the valve housing 16 and the casing 10. A lower drive system passageway 58 extends vertically through the lower actuator block 54 at a position therein between and rearwardly (with respect to relative positions shown in Figure 8) of the shaft and valve liner openings 55 and 56. The drive system passageway 58 also continues vertically through the lower valve head 17 into the interior of the lower pump cylinder 32. Forward and rear exhaust system passageways 59 and 60 extend vertically through the lower actuator block 54 at positions therein eccentric .to the axis of the block and oppositely of the valve liner opening 56.

A lower bypass block 61 is positioned within the valve housing 16 directly above the lower actuator block 54. The shaft opening 55, valve liner opening 56, lower drive system passageway 58 and forward and rear exhaust system passageways 59 and 60, described in the lower actuator block, are vertically continued through the lower bypass block 61. A bypass passageway 62 extends vertically through the lower bypass block 61 at a position therein between and forwardly of the shaft opening 55 and the valve liner opening 56. Within the base of the lower bypass block 61 a recess 63 joining the valve liner opening 56 with the bypass passageway 62 is formed and an orifice 64 communicates the interior of the valve liner 53 with the recess 63. Another recess 65 is formed in the top of the lower bypass block 6-1 and likewise joins the bypass passageway 6-2 with the valve liner opening 56; an orifice 66 through the valve liner '53 communicates this second recess 65 with the interior of the valve liner 53. i j I A lower alternator block. 67 is positioned directly above the lower bypass block 61 and through it are continued the shaft opening 55, valve liner opening 56, lower pressure system passageway 58, bypass system passageway 62, and forward and rear exhaust system passageways 59 and 60. In the top of the lower alternator block 67 a recess 68 communicates the lower pressure system passageway 58 with the valve liner opening 56, and an orifice 6-9 (shown only in Figure 11) in the valve liner 53 communicates the recess 68 with the interior of the valve liner 53. I

' A pressure feed block 70 is positioned within the valve housing 16 directly above the lower alternator block 67 andthrough it are vertically continued the shaft opening 55, valve l-in'er opening 56, bypass system passageway 62, and forward and rear exhaust system passageways 59 and 60. A pressure inlet port 71' communicates the interior of the valve liner 53 within the pressure teed block 70 withthe annulus between the valve housing 16 and the casing through radially aligned openings in the pressure teed block 70, the valve liner 53- and the valve housing 16.

An upper alternator. block 72 is positioned directly above the pressure feed block 70 and through it are continued the shaft opening 55, valveliner opening 56, the bypass passageway 62 and the forward and rear exhaust system passageways 59 and 60.. A recess 73 (Figure 1.1) is formed in the base of the upper alternator block 72 and communicates the valve liner opening 56 with an upper pressure system passageway 74 in vertical alignment with the lower pressure system passageway 58. A corresponding orifice 75 through the valve liner 53 communicates the .recess 73 with the interior of the valve liner 53. It should be noted that the upper and lower pressure system passageways 58 and 74 are respectively continuous above and below the pressure feed block 70 gugclzieither extends into or through the pressure feed An upper bypass block 76 is positioned the valve housing 16 directly above the upper alternator block 72 and Tall openings and passageways extending vertically through the upper alternator block 72 are continued vertically through the upper bypass block 76; in addition, recesses 77 and 78 (Figure 11), each communicating the bypass system passageways 62 with the valve liner opening 56, are respectively formed in the top and base of the upper bypass block 76 and corresponding orifices -79 and 80 are formed through the valve liner 53. All the vertical openings and passageways through the upper alternator block 72 are further continued through an upper actuator block 81 which is positioned within the valve housing 16 directly above the upper bypass block 76. An upper horizontal passageway 82 comprising radially aligned openings through the upper actuator block 8ll, valve liner 53 and valve housing 16 communicates the interior of the valve liner 53 with the annulus between the valve housing 16 and the casing 10. Within the top of the upper actuator block 81, the upper termination of the forward exhaust system passageway 59 is countersunk and a check valve 83 comprising a ball 84 above a valve seat 85 is positioned therein; another check valve 86 (Figure 1) is likewise constructed within the upper termination of the rear exhaust system passageway 60. The upper pressure system passageway 74 is continued vertically through the upper valve head 14 into the upper pump cylinder 24.

' A forward arcuate channel 87 (Figure 9) is formed in the top of the lower valve head 17 and part of the forward arcuate channel is positioned directly beneath the forward exhaust system passageway 59 in the lower actuator block 54. A plurality of oblique passageways 88 are formed through the body of the lower valve head 17 and communicate the forward arcuate channel 87 with the annulus between the lower pump cylinder 32 and the lower divider cylinder 33. A rearward arcuate charinel 89 is similarly formed in theftop of the lower valve head 17 beneath the rearward exhaust system passage= way 60 in the lower actuator block 54 and a plurality of oblique passageways 90 communicate the rearward channel 89 with the annulus between the lower divider cylinder 33 and, the lower pump barrel. 19. In the base of the upper valve head 14 a forward arcuate channel 91 (Figure 3) is formed above the forward exhaust sys upper divider cylinder 25.

and lower horizontal passageways 57 and 82 which communicate the interior of the valve liner 53 with the annulus between the valve housing 16 and the casing 10.

'Upper and lower circular depression plates 98 and 99 are secured to opposite ends of the rod 95 within the valve liner 53, but it should be noted that neither of the circular depression platesmakes pressure tight contact with the interior Wall surface of the valve liner. Each of the sleeve valves 98 and 99 is provided with interior vertical ports 100 (Figure 2A) communicating the space above each sleeve valve with the space there below, but the cylindrical walls of each sleeve valve make pressure tight contact with the interior of the valve liner 53.

A sleeve 101 of outside diameter less than the inside diameter of the valve liner 53 is slidably positioned about the rod 95. An upper blocking valve 102 is coaxially secured to the upper end of the sleeve 101. A lower blocking valve 103 is secured to the lower end of the sleeve 101 and is spaced thereon from the upper blocking valve 102 by a distance slightly less than the distance between the recesses 65 and 78 in the top of the lower bypass block 61 and the base of the upper bypass block 76. A central blocking valve 104 is secured to the sleeve 101 at a position thereon equidistant from the upper and lower blocking valves 102 and 103.

An opening 105 (Figure 3) is vertically disposed through the upper valve head 14 at a position therein slightly inward of the valve liner opening 56 in the upper actuator block :81; a corresponding vertical recess 106 is formed in the upper part of the wall of the upper actuator block 81 and a corresponding vertical slot 107 is adjacently formed in the upper end of the valve liner 53. A pin 108 extends through the opening 105 in the upper valve head 14 and projects, at its opposite ends, into the interior of the upper pump cylinder 24 and into the vertical recess 106 in the upper end of the valve liner opening 56. An actuator disc 109, integrally constructed with the pin 108, projects horizontally from the lower end thereof into the interior of the valve liner 53 above the upper valve depression plate 98. A depression 110 is formed in the base of the upper valve head 14 to acicommodate the upper actuator disc 109 when its pin 108 is fully extended upward. In corresponding construction, a lower pin 111 extends through an opening 112 (Figure 9) in the lower valve head 17 and projects at its opposite ends into the interior of the lower pump cylinder 32 and into a vertical recess 113 adjacent the valve liner opening 56 and within a vertical slot 114 in 7 p the base of the valve liner 53. An actuator disc 115, integrally constructed with the upper end of the lower pin 111, projects horizontally into the interior of the valve liner 53 below the lower depression plate 99. A depression 116 is formed in the top of the lower valve head 17 and is adapted to receive the lower actuator disc 115 when its pin 111 is fully extended downward.

Limiting pins 117 and 118 are respectively positioned above and beneath the central blocking valve 104 and extend horizontally through the valve liner 53 and the pressure feed block 70 to the sleeve 101 within the valve liner. An alignment screw 119 projects from the annulus between the valve housing 16 and the casing 10through the valve housing and threadedly engage the pressure feed block 70.

In operation, fluid is pumped under pressure into the annulus between the tubing 11 and the casing 10 at the surface of the ground. Assuming that the rod 95 and the sleeve 101 are both in their lower positions of travel (as illustrated in Figure 2A) within the valve-liner 53, fluid under pressure enters the pressure inlet port 71 and passes into the interior of the valve liner 53 between the central and upper blocking valves 104 and 102. Each of the blocking valves 102, 103 and 104 completely occupies a portion of the valve liner 53 and blocks the vertical passage of fluid through the portion of the valve liner it occupies. Since the fluid cannot pass around or through the central and upper blocking valves 104 and 102 its only outlet is through the recess 73 in the base of the upper alternator block 72 and thence through the upper pressure system passageway 74 into the interior of the upper pump cylinder 24 below the upper piston 43- Pres sure beneath the upper piston drives that member upwardly and consequently carries the shaft 40 and the lower piston 48 upwardly as well. 'Fluid above the upper piston 43 within the upper pump cylinder 24 is discharged into the tubing 11 through the valve port 30 in the upper cylinder head 26. Fluid above the lower piston 48 within the lower pump cylinder 32 is discharged through the lower pressure system passageway 58 and the recess 68 in the top of the lower alternator block 67 into the interior of the valve liner 53 between the central and lower blocking valves H14 and 103. Since the fluid cannot go through or around the blocking valves 104 and 103 it is forced into the bypass passageway 62 through the recess 65 in the bypass block 61 from which it flows through the upper valve head 14 into the annulus between the upper divider cylinder 25 and the upper pump barrel 13 and then passes into the tubing 11. As the lower piston 48 rises, fluid is drawn into the lower portion of the lower pump cylinder 32 through the lower pump port 38 in the lower cylinder head 34- from the reservoir tube 21.

As the pistons 43 and 48 approach the tops of their respective cylinders 24 and 32, the shoulder 51 of the lower piston 48 engages the lower end of the lower pins 111 and forces the lower actuator disc 115 against the lower depression plate 99 which moves the rod 95 and upper and lower sleeve valves 96 and 97 upward within the valve liner 53 until the upper horizontal passageway 82 is closed and the lower horizontal passageway 57 is opened. Fluid under pressure then enters the lower horizontal passageway 57 and passes upwardly through the vertical ports 10% in the lower sleeve valve 97 within the valve liner 53 below the blocking valve 103 which is then forced upwardly and carries with it the sleeve 101 and central and upper blocking valves 104 and 102. Eluid above the upper blocking valve 102 in' the valve liner 53 is evacuated through the recess 77 in the base of the upper alternator block 72. The upward travel of the sleeve 1031 continues until the central blocking 'valve 104 engages the upper limiting pin 117. With the rod 95 and sleeve 101 at their upper limits of travel, fluid under pressure enters the interior of the valve liner 53 through the pressure inlet port 71 between the central and lower blocking valves 104 and 103 and its exit from the valve liner 53 is confined to the recess 68 in the top of the lower alternator block 67 which conducts the pressured fluid into the lower pressure system passageway 58 and thence into the lower cylinder 32 above the lower piston 48 therein. The motion of the pistons 43 and 48 are thus reversed and fluid below the lower piston 48 within the lower pump cylinder 32 is discharged through the perforations 39 in the lower pump cylinder wall intothe annulus between the lower pump cylinder 32 and the lower divider cylinder 33; from this annulus the fl uid passes through the oblique openings 88 and forward arcuate channel 87 in the lower valve head 17 to the forward exhaust system passageway 59 and thence through the associated check valve 83 and through the forward arcuate channel 91 and oblique passageways in the upper valve head 14 to the annulus between the upper divider cylinder 25 and the upper pump barrel 13 into the tubing 11. Fluid in the lower part of the upper pump cylinder 24 is discharged through the upper pressure system passageway 74 and the recess 73in the base of the upper alternator block 72 into the interior of the valve liner 53 between the central and upper blocking valves 104 and 102 which confine the fluids exit to the recess '78 in the base of the upper bypass block 61 from which it flows into the bypass passageway 62 and thence to the forward arcuate channel 91 in the upper valve head 14 where it joins and is exhausted with the fluid discharged from the lower pump cylinder 32. j

Also during the downward motion of the pistons 43 and 48, fluid is drawn into the upper portion of the upper pump cylinder 24 through the reservoir tube 21 into the annulus between the lower divider cylinder 33 and the lower pump barrel 19 and through oblique passageways and the rear arcuate channel 89 in the lower valve head 17 into the rear exhaust system passageway 60 and its associated check valve 86 and through the rear arcuate channel 93 and oblique passageways 94 of the upper v-alve head 14 into the annulus between the upper pump cylinder 24 and the upper divider cylinder 25 and'then into the upper pump cylinder through perforations 31 in the upper part of the wall thereof.

As the pistons 43 and 48 approach the lower limit of their travel, the shoulder '46 of the upper piston 43 engages the upper end of the upper pin 108 and forces the actuator disc 109 at the lower end of that pin against the depression plate 98 on the upper end of the rod 95. The sleeve valves 96 and 97 are downwardly displaced by this contact and the lower horizontal passageway 57 is thus closed, whereas the upper horizontal passageway 82 is opened and pressured fluid flows downwardly through the upper sleeve valve 96 forcing the upper blocking valve 102 downward and reinstituting thepumping cycle previously described. 1.

The packer 22 prevents fluid pressure from entering the earth reservoir and directs the pressure to the pressure inlet port 71 and to the horizontal passageways 57 and 82. Because the surface applied pressure is so confined in the casing above the reservoir, it is possible to create a partial vacuum in the reservoir by the described action of the pump; hence,- marginal oil wells and certain other types of wells may be pumped by the present invention with particular advantage.

The invention is not limited to the exemplary con struction herein shown and described, but may be made in various ways within the scope of the appended claims.

What is claimed is:

1. In a hydraulic pump including two vertically aligned double acting cylinders spaced from one another and including a single shaft extending between saidcylinders and carrying a piston within each of said cylinders, a vertically disposed valve chamber, an upper intakeport in said valve chamber, a lower intake port in said valve chamber, a central intake port in said valve chamber, means communicating said'upper' and lower and, central Valve ports in said valve chamber with a pressure source,

a rod within said valve chamber, an upper sleeve valve mounted on said rod, a lower sleeve valve mounted on said rod and spaced from said upper sleeve valve by a distance less than the spacing between said upper and lower intake ports, an upper relief port in said valve chamber and spaced from said lower intake port by a distance equaling the spacing between said upper and lower sleeve valves, a lower relief'port in said valve chamber and spaced from said upper intake port by a distance equaling the spacing between said upper and lower sleeve valves, a sleeve slidably mounted on said rod between said sleeve valves, an upper blocking valve mounted on said sleeve, a lower blocking valve mounted on said sleeve, a central blocking valve mounted on said sleeve between said upper and lower blocking valves, an upper exhaust port in said valve'chamber and positioned above said central intake port and spaced from said lower relief port by a distance greater than the spacing between said upper and lower blocking valves, a lower exhaust port in said valve chamber and positioned below said central intake port and spaced therefrom equidistantly with the spacing of said upper exhaust port from said central intake port, an upper pressure drive port in said valve chamber and positioned above said central intake port and spaced therefrom by a distance equaling one-half the distance between said upper and central blocking valves, means communicating said upper pressure drive port with the lower portion of said upper cylinder, a lower pressure drive port in said valve chamber positioned below said central intake port and spaced therefrom by a distance equaling one-half the distance between said lower and central blocking valves, means communicating said lower pressure drive port with the upper portion of said lower cylinder, means communicating said upper and lower relief ports with a the discharge system of said pump, and means actuated by said pistons longitudinally displacing said rod.

2. The invention as defined in claim '1 and wherein said means communicating said upper and lower and central intake ports with a' pressure source comprises the annulus between a well casing and a well tubing and wherein said discharge system of said pump includes the interior of said well tubing.

3. The invention as defined in claim 2 and including a packer disposed around said pump in sealing contact with said casing at a position below said lower intake port.

4. The invention as defined in claim 1 and wherein said valve chamber is positioned between said cylinders eccentrically of and parallel with said shaft.

5. The invention as defined in claim 4 and wherein said means actuated by said pistons longitudinally displacing said rod includes: an upper vertical pin slidably mounted above said valve chamber and extending at its opposite ends into said upper cylinder and into said valve chamber and adapted at its opposite ends for respective engagement with said piston within said upper cylinder and with said rod, and a lower vertical pin slidably mounted below said valve chamber and extending at its opposite ends into said lower cylinder and into said valve chamber and adapted at its opposite ends for respective engagement with said piston within said lower cylinder and with said rod.

References Cited in the file of this patent UNITED STATES PATENTS 

